Breast Cancer Lab Testing: What You Need to Know

Breast Cancer Lab Testing: What You Need to Know

Breast cancer is one of the most common cancers affecting women worldwide. Early detection and accurate diagnosis are crucial for effective treatment and improved prognosis. Various lab tests play a vital role in diagnosing breast cancer, determining its type, and guiding treatment options. This article delves into the different types of lab tests used in the diagnosis and management of breast cancer.

Key Takeaways

  • Different types of biopsies, such as fine-needle aspiration, core-needle biopsy, and surgical biopsy, are used to diagnose breast cancer.
  • Hormone receptor tests, including Estrogen Receptor (ER) and Progesterone Receptor (PR) testing, provide insights into treatment options.
  • HER2/neu testing, using methods like Immunohistochemistry (IHC) and Fluorescence In Situ Hybridization (FISH), helps to determine the aggressiveness of the cancer.
  • Genetic and molecular tests, such as Oncotype DX and BRCA1/BRCA2 testing, offer information on cancer risk and potential treatment plans.
  • Imaging tests like mammography, ultrasound, and MRI, along with blood tests and staging tests, are essential for a comprehensive diagnosis and treatment strategy.

Types of Breast Cancer Biopsies

A biopsy is a procedure in which the doctor obtains a breast tissue or fluid sample from the suspicious area for laboratory analysis. These removed samples are analyzed under a microscope and also tested to check for the presence of cancer cells. A biopsy is the only diagnostic way to confirm if the cells are cancerous, the type of cancer that has developed, and also provide a complete picture of the situation. Three types of biopsy procedures are:

Fine-Needle Aspiration

Fine-needle aspiration (FNA) involves using a thin, hollow needle to remove a small amount of tissue from a suspicious area. This method is often used when the suspicious area is easily accessible and can be felt through the skin. FNA is less invasive than other biopsy methods and usually does not require anesthesia.

Core-Needle Biopsy

A core-needle biopsy uses a larger needle to remove a core of tissue from the suspicious area. This method provides more tissue for analysis compared to FNA, which can be crucial for determining the type of breast cancer. Core-needle biopsies are often performed under local anesthesia and may be guided by imaging techniques such as ultrasound or mammography.

Surgical Biopsy

For a surgical biopsy, a surgeon removes part (incisional biopsy) or all (excisional biopsy) of a lump for evaluation under a microscope. If the lump is small or hard to locate by touch, the surgeon may use a procedure called wire localization to map out a route to the mass prior to the surgery. Surgical biopsies are more invasive and usually require general anesthesia.

Understanding the different types of breast cancer biopsies can help you and your healthcare team choose the most appropriate method for your situation.

Hormone Receptor Testing

Hormone receptor testing is a crucial step in the diagnosis and treatment of breast cancer. This test identifies whether the cancer cells have receptors for the hormones estrogen and progesterone. These receptors are specialized proteins located on the surface of or within a cell. When these hormones bind to their respective receptors, they signal the cell to start growing and multiplying. Understanding the hormone receptor status of a tumor can provide insight into which cancer treatment options may be most effective.

Estrogen Receptor (ER) Testing

Estrogen receptor (ER) testing is performed to determine if breast cancer cells have receptors for the hormone estrogen. If the cancer is ER-positive, it means that the cancer cells may receive signals from estrogen that could promote their growth. This information is vital for deciding on hormone therapy as a treatment option.

Progesterone Receptor (PR) Testing

Progesterone receptor (PR) testing is similar to ER testing but focuses on the hormone progesterone. If the cancer is PR-positive, it indicates that the cancer cells may grow in response to progesterone. Like ER testing, PR testing helps in tailoring hormone therapy for the patient.

Hormone receptor testing is generally recommended for all breast cancers, including DCIS. If your doctor orders this test, you may be asked to discontinue taking any prescribed hormones for a period of time before the breast tissue sample is obtained. Usually, the sample comes from a biopsy, but the test may also be performed on tissue removed during a lumpectomy or mastectomy.

HER2/neu Testing

HER2/neu testing is crucial for determining the presence of the HER2 protein or an excessive number of copies of its gene in breast cancer cells. This test is particularly recommended if you have been diagnosed with invasive breast cancer or have had recurrent breast cancer. The results of this test will help your oncology team determine your prognosis, the characteristics of the tumor, including how aggressive it is likely to be, and the best treatment options.

Immunohistochemistry (IHC)

The IHC test, short for ImmunoHistoChemistry, examines whether there is an excess of HER2 protein in the cancerous cells. The results are categorized as follows:

  • 0 or 1+: No excess HER2 protein
  • 2+: Borderline
  • 3+: Positive for HER2 protein overexpression

Fluorescence In Situ Hybridization (FISH)

FISH testing is another method used to determine the HER2 status of breast cancer cells. This test looks at the number of copies of the HER2 gene in the cancer cells. The results can be:

  • Positive: Indicates HER2 gene amplification
  • Negative: Indicates the number of HER2 genes is not excessive
  • Low: Provides some patients with advanced breast cancer the opportunity to receive therapy specific for HER2/neu positive breast cancer patients
The HER2/neu test can discover whether the sample is normal or whether it has too much of the HER2/neu protein or an excessive number of copies of its gene. This information is vital for tailoring the most effective treatment plan for the patient.

Genetic and Molecular Testing

Genetic and molecular testing play a crucial role in understanding the underlying factors contributing to breast cancer. These tests can provide insights into the genetic mutations and molecular characteristics of the cancer, which can guide treatment decisions and risk assessment. If your gene test was done more than five years ago, your healthcare team might recommend testing again with newer tests. Additionally, if your family health history changes, such as if additional family members develop cancer, your team might recommend additional genetic testing.

Genetic testing is an active area of research. If you find that you are at high risk for breast cancer, there are preventive measures you can take.

Oncotype DX

Oncotype DX is a genomic test that analyzes the activity of a group of genes in a breast cancer tumor. This test helps to predict the likelihood of breast cancer recurrence and whether a patient will benefit from chemotherapy. The results of the Oncotype DX test can be crucial in making informed treatment decisions.

BRCA1 and BRCA2 Testing

BRCA1 and BRCA2 are genes that, when mutated, significantly increase the risk of developing breast cancer. Testing for these mutations involves collecting blood, saliva, or a cheek scraping. If you are concerned about your risk for developing breast cancer, you may want to see a genetic counselor and discuss getting a genetic test. Genetic counseling can help you understand what the results could mean for your health.

Other Gene Expression Tests

Other gene expression tests, also known as biomarker tests, can be done on tissue taken during a biopsy or surgery for breast cancer. If the biopsy sample is too small and all the molecular tests cannot be done, the testing may also be done on blood that is taken from a vein just like a regular blood draw. This blood contains the DNA from dead tumor cells (known as circulating tumor DNA), which can be analyzed to provide additional insights into the cancer's characteristics.

Imaging Tests for Breast Cancer

Mammography is the most common imaging test used to detect breast cancer. It involves taking X-ray images of the breast to identify any abnormalities. If your doctor finds an area of concern on a screening mammogram, you may need additional tests to determine if it is cancer. Mammograms are particularly effective for early detection and can significantly improve the chances of successful treatment.

Breast ultrasound uses sound waves to create images of the inside of the breast. This test is often used to further evaluate abnormalities found during a mammogram or physical exam. Ultrasound is particularly useful for distinguishing between solid masses and fluid-filled cysts. It is a non-invasive procedure and does not involve exposure to radiation.

Magnetic Resonance Imaging (MRI) is a highly sensitive imaging test that uses magnetic fields and radio waves to produce detailed images of the breast. MRI is often recommended for individuals at higher risk of breast cancer or to assess the extent of the disease after a diagnosis. It can also be used as a follow-up to a mammogram or ultrasound when more detailed information is needed.

MRI can be particularly useful in identifying cancer, the extent of the disease, and other abnormalities, making it a valuable tool in breast cancer diagnosis and management.

Blood Tests in Breast Cancer Diagnosis

breast cancer lab testing blood tests diagnosis

Blood tests are not used to diagnose breast cancer, but they can help to get a sense of a person’s overall health. For example, they can be used to help determine if a person is healthy enough to have surgery or certain types of chemotherapy.

Complete Blood Count (CBC)

A Complete Blood Count (CBC) is a common blood test that measures different components of the blood, including red blood cells, white blood cells, and platelets. This test can help detect anemia, infection, and other conditions that might affect treatment.

Liver Function Tests

Liver function tests are blood tests that can help find if some of your organs, such as the liver, are not working as well. For example, if cancer has spread to the liver, it can sometimes cause high levels of liver function tests, such as aspartate aminotransferase (AST) or alanine aminotransferase (ALT).

Tumor Markers

Tumor markers are substances found at higher than normal levels in the blood, urine, or tissues of some people with cancer. In breast cancer, common tumor markers include CA 15-3 and CA 27.29. These markers can help monitor the effectiveness of treatment or detect a recurrence of cancer.

Blood tests provide crucial information about a patient's overall health and can guide treatment decisions, even though they are not used to diagnose breast cancer directly.

Staging and Prognostic Tests

Tumor profiling involves analyzing the genetic and molecular characteristics of the cancer cells. This helps in understanding the aggressiveness of the tumor and predicting how it might respond to certain treatments. Tumor profiling can include tests like Oncotype DX and MammaPrint, which provide a recurrence score that helps in making treatment decisions.

Lymph node analysis is crucial in staging breast cancer. It involves examining the lymph nodes near the breast to check for the spread of cancer. This can be done through a sentinel lymph node biopsy or an axillary lymph node dissection. The presence of cancer cells in the lymph nodes often indicates a higher stage of cancer and may influence the treatment plan.

Positron Emission Tomography (PET) and Computed Tomography (CT) scans are imaging tests used to stage breast cancer. These scans provide detailed images of the inside of the body and help in detecting the spread of cancer to other organs. PET scans are particularly useful for identifying active cancer cells, while CT scans provide a detailed view of the tumor's size and location.

Understanding the stage of breast cancer is essential for determining the prognosis and the most effective treatment options. The stage is determined based on the size of the tumor, its location, and whether it has spread to lymph nodes or other parts of the body.

Frequently Asked Questions

What are the different types of breast cancer biopsies?

The different types of breast cancer biopsies include fine-needle aspiration, core-needle biopsy, and surgical biopsy.

What is hormone receptor testing in breast cancer?

Hormone receptor testing in breast cancer involves checking the cancer cells for receptors for hormones like estrogen and progesterone. This helps in determining the best treatment options.

What is HER2/neu testing?

HER2/neu testing involves checking for the presence of the HER2 protein on the surface of breast cancer cells. This can help guide treatment decisions.

What genetic and molecular tests are available for breast cancer?

Genetic and molecular tests for breast cancer include Oncotype DX, BRCA1 and BRCA2 testing, and other gene expression tests. These tests provide information on the genetic makeup of the cancer.

What imaging tests are used for breast cancer diagnosis?

Imaging tests used for breast cancer diagnosis include mammography, ultrasound, and MRI. These tests help in visualizing the breast tissue and identifying any abnormalities.

What blood tests are done in breast cancer diagnosis?

Blood tests in breast cancer diagnosis may include a complete blood count (CBC), liver function tests, and tumor markers. These tests provide information on overall health and the presence of cancer-related substances in the blood.

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